extracted rejectChanges to a separate file

GitOrigin-RevId: 83c55c4823f6e18f22dbd6bc1fa7ec010c509e30
2026-11-14 06:03:45 +01:00 · 2024-08-26 08:05:10 +00:00
parent ea20f82ad6
commit cab58d87dd
3 changed files with 110 additions and 114 deletions
@@ -0,0 +1,106 @@
+import { EditorState } from '@codemirror/state'
+import { Change, EditOperation } from '../../../../../../types/change'
+import { isDeleteOperation, isInsertOperation } from '@/utils/operations'
+import { DocumentContainer } from '@/features/ide-react/editor/document-container'
+import { trackChangesAnnotation } from '@/features/source-editor/extensions/realtime'
+
+/**
+ * Remove tracked changes from the range tracker when they're rejected,
+ * and restore the original content
+ */
+export const rejectChanges = (
+  state: EditorState,
+  ranges: DocumentContainer['ranges'],
+  changeIds: string[]
+) => {
+  const changes = ranges!.getChanges(changeIds) as Change<EditOperation>[]
+
+  if (changes.length === 0) {
+    return {}
+  }
+
+  // When doing bulk rejections, adjacent changes might interact with each other.
+  // Consider an insertion with an adjacent deletion (which is a common use-case, replacing words):
+  //
+  //     "foo bar baz" -> "foo quux baz"
+  //
+  // The change above will be modeled with two ops, with the insertion going first:
+  //
+  //     foo quux baz
+  //         |--| -> insertion of "quux", op 1, at position 4
+  //             | -> deletion of "bar", op 2, pushed forward by "quux" to position 8
+  //
+  // When rejecting these changes at once, if the insertion is rejected first, we get unexpected
+  // results. What happens is:
+  //
+  //     1) Rejecting the insertion deletes the added word "quux", i.e., it removes 4 chars
+  //        starting from position 4;
+  //
+  //           "foo quux baz" -> "foo  baz"
+  //                |--| -> 4 characters to be removed
+  //
+  //     2) Rejecting the deletion adds the deleted word "bar" at position 8 (i.e. it will act as if
+  //        the word "quuux" was still present).
+  //
+  //            "foo  baz" -> "foo  bazbar"
+  //                     | -> deletion of "bar" is reverted by reinserting "bar" at position 8
+  //
+  // While the intended result would be "foo bar baz", what we get is:
+  //
+  //      "foo  bazbar" (note "bar" readded at position 8)
+  //
+  // The issue happens because of step 1. To revert the insertion of "quux", 4 characters are deleted
+  // from position 4. This includes the position where the deletion exists; when that position is
+  // cleared, the RangesTracker considers that the deletion is gone and stops tracking/updating it.
+  // As we still hold a reference to it, the code tries to revert it by readding the deleted text, but
+  // does so at the outdated position (position 8, which was valid when "quux" was present).
+  //
+  // To avoid this kind of problem, we need to make sure that reverting operations doesn't affect
+  // subsequent operations that come after. Reverse sorting the operations based on position will
+  // achieve it; in the case above, it makes sure that the the deletion is reverted first:
+  //
+  //     1) Rejecting the deletion adds the deleted word "bar" at position 8
+  //
+  //            "foo quux baz" -> "foo quuxbar baz"
+  //                                       | -> deletion of "bar" is reverted by
+  //                                            reinserting "bar" at position 8
+  //
+  //     2) Rejecting the insertion deletes the added word "quux", i.e., it removes 4 chars
+  //        starting from position 4 and achieves the expected result:
+  //
+  //           "foo quuxbar baz" -> "foo bar baz"
+  //                |--| -> 4 characters to be removed
+
+  changes.sort((a, b) => b.op.p - a.op.p)
+
+  const changesToDispatch = changes.map(change => {
+    const { op } = change
+
+    if (isInsertOperation(op)) {
+      const from = op.p
+      const content = op.i
+      const to = from + content.length
+
+      const text = state.doc.sliceString(from, to)
+
+      if (text !== content) {
+        throw new Error(`Op to be removed does not match editor text`)
+      }
+
+      return { from, to, insert: '' }
+    } else if (isDeleteOperation(op)) {
+      return {
+        from: op.p,
+        to: op.p,
+        insert: op.d,
+      }
+    } else {
+      throw new Error(`unknown change type: ${JSON.stringify(change)}`)
+    }
+  })
+
+  return {
+    changes: changesToDispatch,
+    annotations: [trackChangesAnnotation.of('reject')],
+  }
+}